When donuts have fully cooled, about 20-30 minutes after removing them to the cooling rack, they are ready to be glazed. Place your cooling rack on top of a cookie sheet.
In a shallow bowl, whisk all ingredients beginning with only 1 tbsp of milk until smooth. If the glaze is too thick, add milk a little bit at a time until the desired consistency is reached. You want the glaze to be slightly thick but not too runny otherwise it will run off of the donuts.
After glazing, return the donuts to the cooling rack so that excess glaze can drip into the cookie sheet. Allow the glaze to harden for 30 minutes or so.
Serve and enjoy!